In human sexual behavior, promiscuity refers to the practice of having many sexual partners in the absence of any commitment and promiscuous is a term applied to a person who has had sex with relatively many partners. Polygamy is distinguished from promiscuity in that the former refers to numerous romantic relationships, whether sexual or not, while the latter refers simply to sexual activity, without there necessarily being any further connection between the individuals involved.

Promiscuity is common in many animal species. Some species have promiscuous mating systems, ranging from polyandry and polygyny to mating systems with no stable relationships where mating between two individuals is a one-time event. Many species form stable pair bonds but still mate with other individuals outside the pair. In biology, incidents of promiscuity in species that form pair bonds are usually called extra-pair copulations.

Human promiscuity

What sexual behavior is considered socially acceptable and what behavior is "promiscuous" varies much among different cultures, and within a culture, and different standards are often applied to people of different gender and civil status. In many cultures, while male promiscuity previously had glamorous connotations that acted as an affirmation of masculinity, female promiscuity was seen as a sign of emotional instability and loose morals in women.

Accurately assessing people's sexual behavior is difficult, since there are strong social and personal motivations, depending on social sanctions and taboos, for either minimizing or exaggerating reported sexual activity. Extensive research has produced mathematical models of sexual behavior comparing the results generated with the observed prevalence of sexually transmitted infections (STIs) to statistically estimate the probable sexual behavior of the studied population.

The number of sexual partners an individual has varies within a lifetime, and varies widely within a population. In the U.S., a 2007 national survey had the following results: the median number of lifetime female sexual partners reported by men was seven; the median number of male partners reported by women was four. It is possible that men exaggerated their reported number of partners, women reported a number lower than the actual number, and/or a minority of women had a sufficiently larger number than most other women to create a mean significantly higher than the median. Twenty-nine percent of men and nine percent of women reported to have had more than 15 sexual partners in their lifetimes.[1] Studies of the spread of STIs consistently demonstrate that a small percentage of the studied population have more partners than the average man or woman, and a smaller number of people have fewer than the statistical average. An important question in the epidemiology of sexually transmitted infections is whether or not these groups copulate mostly at random (with sexual partners from throughout a population) or within their social groups (assortative mixing).